Strip foam boat building

Discussion in 'Boatbuilding' started by svfrolic, Jan 14, 2013.

  1. TeddyDiver
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    TeddyDiver Gollywobbler

    Yes David, thanks for the links. And to answer your question, yes the method could be used for canoes, but caveat in small vessels with light and relatively "soft" core the skins might need to be over engineered and you get more weight penalty (and cost) than with some other higher density core that might also carry a part of the stuctural loads. However all this is very case sensitive and just "cooking up" the schedules with random materials like the OP intends has very little odds to success..
     
  2. svfrolic
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    svfrolic Junior Member

    Great, nice too see some solid information eventually. I knew this surfboard builders must know what they are doing.
    I know that bending already glassed strips might be a problem. Probably it would be overkill for a small boat anyway.
    I don't have a female mold and don't want to build one unless I know that I like this boat and want start making it so the idea of the core.
    So canoes in your club are only single or double layer of Kevlar? Is it 5oz. fabric or heavier?
     
  3. svfrolic
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    svfrolic Junior Member

    I have just started my research. This thread is part of it. So what exactly is a stupid choice: building at all or building method..?
     
  4. Oyster
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    Oyster Senior Member

    Yep!,,,,,, Comparing a big cat to building a one off canoe using a simular method does not stand up to common sense for anyone wanting a liteweight portable canoe either. While you may end up with a hull shaped however you want it to be, other people have tried it for small craft and ends up cutting them up.

    Using a surfboard in an attempt to compare what should be done in a boat hull is at best flawed too. But writing a reply will probably not be worth the effort. Over and out,,
     
  5. TeddyDiver
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    TeddyDiver Gollywobbler

    Good for you :)
    Neither.. When you know what you are doing and why you are using a specific building method you are fine :D
    BR Teddy
     
  6. kvsgkvng
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    kvsgkvng Senior Member

    Look I am going through same motions as we speak, I also would like to build "a small boat." Investigating all options, I think that purchasing a used boat is the way of least resistance. It would be the biggest bang for your buck so to speak. This all relates to the final goal to have "a small boat" and get on the water ASAP.

    It is entirely different matter if one's ego is involved. Then it is a looooong and thorny way to compete with all other players around. And some of those players are not playing clean and fair sometimes (wink, wink).

    I may attest that it is extremely difficult to come up with a fresh novel idea because a lot of stuff has been already done in all of traditional areas. Most of the stuff has been published on the net, it just takes time and effort to search cost/benefit cause and decide what is most important.

    If you come up with some helium filled cargo ballons powered by deep_sea/hot_air temperature differential electrical drive then please sign me in as your technical director on a fixed salary in your newly formed company.

    Otherwise most of currently known stuff has been already done.

    Answer: 5 oz cloth is fine for canoe sized boat, single ply or double depends on either the boat would have internal ribs/bulkheads and in ether case is addressable after the boat is complete.
     
  7. Ilan Voyager
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    Ilan Voyager Senior Member

    For a small canoe, strip foam and composite offer very little gain over a strip wood: it's just basic maths as the surfaces involved are very small. The price is at least two to three times more expensive.
    That asks far more time: you have to make a very precise jig as the foam strips offer little rigidity.
    Fairing is pretty tricky and if you are not skilled in this method you'll be surprised by the weight of the putty used. Often there is no weight savings compared with wood.

    Forget about PU foam, it doesn't last, and the shear modulus is too low. You need a good PVC foam, better if reticulated with a density of at least 80 kg/m3. You'll be afraid by the price...and sold by complete box.

    About the assertion of a week end project, it must be a very long week end. A such boat in composite one off asks for at least 120 hours because of the jigs or molds. 120 hours if you're a good one...I do like all these over optimistic labor estimations, it's already impossible as the resins have to cure...

    Last but not the least...a wood strip can be made by any amateur with reasonable skills and little tooling. A good composite is often beyond the knowledge of the common amateur, specially when engineering is involved.
    Lindahl has more than 30 years of experience, sure he knows to use a squeege. Vacuum on a "small cat" is useless if the builder is skilled. Always the maths, not enough surface and fiber involved to get a gain to justify the over cost of vacuum...

    I assume you're an amateur, as a pro or quasi pro wouldn't be here asking for this kind of information...
     
  8. michael pierzga
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    michael pierzga Senior Member

    Also remember that working with wood strips is fun !!

    Boatbuilding should be fun...not a science project, dust devil

    white cedar smells nice and when you run your hand plane down a plank edge it makes great swirls of wood on the shop floor. Keep the swirls...perfect for your fireplace.



    And stay away from kevlar...nasty stuff when you work with it and double nasty stuff next year when you fix it.. Lightweight Sglass cloth is easy to use and makes a really tough skin.
     
  9. Oyster
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    Oyster Senior Member

    Yep,[Juniper in our part of the world] and you can make them as long as you wish, off the jig, scarfing them and then resaw them. With the shavings from planing them down, you have a nice carpet even in the dirt floor of a working area.
    [​IMG]
     
  10. Ilan Voyager
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    Ilan Voyager Senior Member

    I do agree. Cedar smells good and it's a dream to work. Kevlar is very nasty. That begins with cutting it, it's impregnates badly, and it's impossible to sand. No need of S glass, a common cheap E glass, a 6 to 10 oz satin is largely enough for a canoe.
     
  11. groper
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    groper Senior Member

    Im surprised nobody has posted this yet???

    To the OP, i suggest you read this, there is gold information pertaining to this building method inside;

    Diab foam strip planked one off construction method

    I also prefer to work with high density foam as opposed to wood... its easier to sand, and i find its generally very pleasant to work with, nice and light, cuts and mills nicely etc... Long boarding the raw foam strips before glassing is a snap... sure its more expensive, but i dont see it as anyone elses business knowing how deep ones pockets are...
     
  12. Oyster
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    Oyster Senior Member

    I don't care, but as with others we have pointed out pitfalls for what you end up with for the work and costs. The context is everything. There are some downsides to certain methods, depending on a particular hull and size in particular, and has been pointed out. If its all about a mental excersize of sorts to say that you did something, by all means go for it. All one needs to do is to look at the several examples of just building the jig for a one off car topper too of sorts, for what you will end up with, and say is it worth it. People cringe at the price of quality foam board and think that they are saving money by using home insulation stuff. Yet they will need to spend bunches of money on epoxy resin if you use the cheap stuff too, because polyester resin eats the trash stuff too. Pink board, as was represented can be used for creating boat parts with the correct setup that compensates for the weak compression rating. But these threads should be more informative than just say what the heck, go for it.
     
  13. kvsgkvng
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    kvsgkvng Senior Member

    Owens Corning "Pink" High Density Foams "Foamular" 400,600,1000

    The “Pink” stuff is no slouchy either. Just look at the attached brochure and you can see that the “pink goo” is tough enough. It is the same polystyrene foam with pretty the same specs. If it is “pink” it doesn’t mean that it is that packing foam which you can squeeze with your palm. It is pretty tough if it is used in airport pavement runways. My choice would be Grade 600, again it is 60 psi foam, pretty rigid, small bubble cavities, easily workable, holds good shape when thincker than ½"
    ... and it is pink!
     

    Attached Files:

  14. svfrolic
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    svfrolic Junior Member

    I spoke to the guy who built strip foam boat and he had the same opinion about how easy is to work with foam.
    Thanks for good link!
    A lot of people point how time consuming is to build molds and jig but you can actually buy CNC cut canoe molds for 200-300$.
     

  15. kerosene
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    kerosene Senior Member

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